Boats, especially fishing boats, often provide pairs of side-by-side seats removably mounted to vertical posts. FIG. 1 shows such an arrangement. In this illustration, an open fishing boat 1 has a center console 2 in front of which two seats 3 are disposed side-by-side. The seats 3 are removably mounted atop vertical posts 5. The posts 5 are secured to the deck 4 by mounting bases 6. Each mounting base 6 is fixed to the deck 4, by screws or bolts. Because boats come in many styles and sizes from a variety of different manufacturers, the spacing between posts 5 varies.
Individual seats of the general type shown as 3 in FIG. 1 are not designed to be useful for other purposes, such as holding fishing rods, providing storage, offering gripping bars, and other similar purposes. It is sometimes desirable to substitute a bench for the seats in order to provide a sitting and leaning surface that also provides a variety of other useful functions. These benches are generally known as a “leaning post”. The wider leaning posts require two vertical posts for support. Because many boats include two, side-by-side vertical posts 5 for individual seats, these can be used to support a leaning post bench. However, these pairs of side-by-side posts 5 are fixed by mounting bases 6 to the deck 2 of a boat 1 at different spacings for each boat. To substitute a leaning post bench for the individual seats 3, the mounting brackets under the leaning post bench must be adapted to the spacing provided by the posts on a particular boat. Usually, the boat owner must measure the spacing between the seat posts 5, then fix the mounting brackets to the bottom of the leaning post bench. This mounting process can involve drilling holes into the bottom of the leaning post bench and requires careful measurement and installation. This is not a simple undertaking for many boat owners.